1. The transfer of VLDL-associated phospholipids to activated platelets depends upon cytosolic phospholipase A2 activity
- Author
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Ibrahim, Salam, Calzada, Catherine, Pruneta-Deloche, Valérie, Lagarde, Michel, Ponsin, Gabriel, Vericel, Evelyne, Régulations métaboliques, nutrition et diabètes (RMND), Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
MESH: Egtazic Acid ,MESH: Estrenes ,lipoprotein lipase ,MESH: Phosphonic Acids ,MESH: Pyrrolidinones ,MESH: Thrombin ,MESH: Cytosol ,MESH: Arachidonic Acids ,MESH: Platelet Activation ,MESH: Lipoproteins, VLDL ,MESH: Aspirin ,MESH: Phospholipases A2 ,MESH: Blood Platelets ,MESH: Umbelliferones ,MESH: Phospholipids ,Ca++-independent phospholipase A2 ,MESH: Humans ,MESH: Phospholipid Transfer Proteins ,MESH: Naphthalenes ,thrombin ,metabolic inhibitors ,[SDV.AEN] Life Sciences [q-bio]/Food and Nutrition ,lipids (amino acids, peptides, and proteins) ,MESH: Phospholipases A ,[SDV.AEN]Life Sciences [q-bio]/Food and Nutrition ,MESH: Pyrones ,MESH: Lipoprotein Lipase - Abstract
International audience; We previously reported that VLDL could transfer phospholipids (PLs) to activated platelets. To identify the metabolic pathway involved in this process, the transfer of radiolabeled PLs from VLDL (200 microM PL) to platelets (2 x 10(8)/ml) was measured after incubations of 1 h at 37 degrees C, with or without thrombin (0.1 U/ml) or LPL (500 ng/ml), in the presence of various inhibitors, including aspirin, a cyclooxygenase inhibitor (300 microM); esculetin, a 12-lipoxygenase inhibitor (20 microM); methyl-arachidonyl-fluorophosphonate (MAFP), a phospholipase A(2) (PLA(2)) inhibitor (100 microM); 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis (acetoxymethyl) ester (BAPTA-AM), a Ca(2+) chelator (20 microM); bromoenol lactone (BEL), a Ca(2+)- independent phospholipase A(2) (iPLA(2)) inhibitor (100 nM); and 1-[6-[[17beta-3-methoxyestra-1,3,5(10)-trien-17-yl-]amino]hexyl]1H-pyrrole-2,5-dione (U73122), a phospholipase C (PLC) inhibitor (20 microM). Aspirin and esculetin had no effect, showing that PL transfer was not dependent upon cyclooxygenase or lipoxygenase pathways. The transfer of PL was inhibited by MAFP, U73122, and BAPTA-AM. Although MAFP inhibited both cytosolic phospholipase A(2) (cPLA(2)) and iPLA(2), only cPLA(2) is a calcium-dependent enzyme. Because calcium mobilization is favored by PLC and inhibited by BAPTA-AM, the transfer of PL from VLDL to platelets appeared to result from a cPLA(2)-dependent process. The inhibition of iPLA(2) by BEL had no effect on PL transfers.
- Published
- 2007
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